Due to concerns for energy conservation, three has been a recognized need for control devices for automatically switching electric power. Electronic timers for automatically controlling the on and off cycles of appliances or outdoor lights are an example. In order to reduce wiring and installation costs, power switching controllers have been adapted for installation in a standard circuit breaker panel. U.S. Pat. No. 4,272,687 to Borkan discloses a single-pole device for this purpose, and U.S. Pat. No. 4,754,162 to Kundou, et al. discloses a multi-pole device. A disadvantage of these devices is that both include a power switching controller and circuit breaker integrated within a circuit breaker housing that attaches to the breaker panel. As a result, each device must be produced in all the standard ampere ratings desired, in order to be used in a specific application. Further, they must be produced in various housings and configurations required by the available circuit breaker panels. Both of these objections result in higher production costs and subsequent lower utilization.